Means for testing metals



Aug. 6, 1935- H. T. HALLOWELL, JR

MEANS FOR TESTING METALS Filed July '30, 1932 2 Sheets-Sheet 1 1935- H. T. HALLOWELL, JR 2,010,189

MEANS FOR TESTING METALS Filed July 30, 1932 2 Sheets-Sheet 2 l my m/ Patented Aug. 6 19 35 I UNITED STATES PATENT OFFICE MEANS FOR TESTING METALS Howard T. Hallow'ell, Jr., Jenkintown, Pa., as-

signor to Standard Pressed Steel 00., Jenkin town, Pa., a corporation of Pennsylvania Application July 30, 1932, Serial No. 626,982

2 Claims. (01. 175-183) This invention relates to systems for determin- A second pair of similar coils H and I2 are ining the physical and/or chemical characteristics ductively associated respectively with coils I and of ametal piece by comparison with a standard 2. The inductively associated pairs of coils I, ll metal piece of known characteristics. and 2, l2 are arranged so -that the unknown piece 5 The general object of the invention is to pro- :c and the standard piece s may be' conveniently 5 vide an improved system which is very accurate brought into inductive relation with them, as in determining the physical and/or chemical illustrated, so that the metal pieces and coils concharacteristics of a. metal piece and in which stitute magnetic core transformers. The imthere is provided means for visually indicating portant physical characteristics of a piece of the characteristics of the said piece. magnetic metal, such as hardness, elasticity, 10

A more specific object of the invention is to te city, du y. freedom n Cracks, as provide a system which utilizes oscillographic well as the chemical characteristics of the piece, means for producing an image pattern which is directly aflect the magnetic characteristics of the symbolic of the characteristics of the metal piece piece. It will be quite apparent then that the under observation. physical and/or chemical characteristics of the 15 With these and other objects in view, the intwo magnetic pieces will determine the potentials vention in its preferred form consists in the novel set up ss ils II and H y v r u of y features of construction and arrangement of potentials existing across coils l and 2. parts illustrated on the accompanying drawings Coils II and I2 are serially connected but in and described hereinafter. In the drawings: opposed relation as illustrated. The extremities 20 Fig. l is a schematic wiring diagram of the sysof these coils are connected to the primary l3 of tem; transformer I4. A suitable condenser l5, pref- Fig. 2 is a perspective view of the main cabinet ra ly of tw r a ad ap a d w t E or housing of the device which houses certain a al y Connected across the P y Windessential elements of the system; ing l3. The transformer secondary winding I1 25 Fig. 3 is a perspective view of a preferred f rm is connected to the control grid and cathode or of pick-up device; and filament of an amplifying tube 1;. This tube may Figs. 4 to 8 illustrate image patterns of five take any desired form,.but is shown herein as an difierent pieces of metal, indicating clearly the r ry hr e-el rode b for the sake of simao differences of the characteristics thereof. p i The u ual d ia fi t sup y. a

Referring t 1, there is Shown at piece plate or anode supply sources are illustrated reof magnetic metal, such as te l, th physical spectively at l8, l9 and 20. While these sources characteristics of which it is desired to deterare shown herein for the Sa e of simp ic y a mine. A standard piece of similar metal is illus- Separate batteries, vthe necessary -di o a trated at s, the physical characteristics of this Potential-S ay. of u s be d ved fr m a 35 piece being known. A pair of similar primary Single s e. 1: even frOm the al rn in 1- coils I and 2 are seriallyconnectedin circuit with rent Source above mentioned y using Suitable the secondary winding 3 of transformer 4. 1nrectifying and filte q pment. The plate cluded in this series circuit, is a, jack 5 h t d b output circuits of the amplifier tube is completed a switch 6, the purpose of whi h il b more through the primary winding 2| of transformer 40 clearly apparent hereinafter. The primary 1 of 22 inv known fash A j 3 shunted y the transformer 4 is energized fro li a hi switch 24 is provided in this circuit and functions maybe connected to any suitable source of elec- 88 Clearly explained e e trical energy (not shown), preferably a 110 t, In accordance with the present invention, there 60 cycle alternating-current source, such as is is Provided 8 Braun cathode ay t b 25 5 commonly used commercially." There is conprising the usual glass envelope 5, W n w ch nected also across line conductors 8 a potentiomare disposed ecathcde 21, an anode and Pairs eter or voltage divider 8, whose purpose will be of ayfl n Plates 29 d 30, the d Pairs explained later. It will be apparent that the of p ates being arranged in Planes at right angles voltage divider is in parallel relation with the t a cther- There is also provided a suitable 60 transformer primary 1 so that both these elescreen 3|, which is preferably located within the ments are supplied with energy from a common as e op a t e ged end thereof, source. A pilot light I0 is also connected across though it is to be understood that this screen the supply lines to indicate the operative condimay be located outside the glass envelope if tion of the system. desired. The screen may be of any suitable ma- 66 terial which will give a clearly defined image of the path of the ray which is indicated by broken lines at 32;

The cathode 2'! may be supplied with energy from source I9 and to this end suitable connecrived from the source 29 via conductor 35. The

secondary winding 36 of transformer 22 has one extremity connected to one of plates.30 at 31,

while its other extremity is connected to anode 28, one of plate 29 and the other of plates 36.

"Movable contacts 38 and 39 form a part of the voltage divider 9 and engage the resistance thereof at adjustable spaced points. Contact 38 is connected, via conductor 40, to anode 28 and the plates 29 and 30 to which the lower extremity of secondary 36 is connected. Contact 39 is connected, via conductor 4|,to the other of plates 29.

By virtue of this arrangement, any voltage or potential appearing across secondary 36 is applied between plates 36, while any potential appearing across the eifective portion of the resistance of voltage divider 9 is applied between plates 29. With the cathode ray tube in operation, the path of the ray will depend upon these respective voltages, as is well known. Since supply lines '8 are connected to a suitable source of alternating current of constant frequency, such for example as commercial 60 cycle current, a fluctuating potential of desired amplitude may be derived by voltage divider 9 and applied'between plates 29..

The charges thus applied to plates 29 will cause the ray to oscillate back and forthbetween these plates due to the successive alternating of the polarity of the charges. If now a potential is applied between plates 30 also, then the path of the cathode ray instead of being a substantially straight line between plates 29 will be modified to give a path taking the form of a closed figure.

Let us assume now that the unknown and standard pieces a; and s are properly positioned with respect to their coil pairs and that switches 6, 24 and 33 are closed. The voltage across supply lines 8 being supplied to transformer 4 will result in a certain voltage being set up across secondary i3. Current will fiow in the series-circuit comprising winding 3 and coils I and 2 and opposing voltages will be set up across coils l and 2.

It is essential that the coils be designed so that the opposing voltages will be substantially equal if the magnetic cores are similar. The coils will preferably be identical with each other, but this is not necessary so long asthe above stated condition is fulfilled If pieces a: and s are of identical physical and chemical characteristics, the voltagesinduced across coils H and I2 will be exactly equal and since they oppose each other, they-will neutralize each other. As a consequence, substantially no current will flow in the circuit comprising these coils and no energy will If, however, there is any difierence, between the characteristics of pieces :c-and s, such difierence will be reflected in the opposing voltages induced across coils I I and i2 and a resultant voltage will be applied to transformer II; the amplitude of which will be proportionalto' the difference in characteristics of the two pieces. The resultant voltage will be applied to tube 1: which serves to amplify it. The amplified resultant voltage will then be applied between plates 30 as above set forth. By viewing screen 3|, the path of the cathode ray may be readily ascertained and an observer can determine at once whether or not there is any appreciable difference between the unknown and standard pieces. In the event that they are practically identical, the observer will see a substantially straight line orrlat closed figure as the image pattern representing the ray path. On the other hand, any difference in the, characteristics of the pieces will divulge itself in the image pattern appearing on screen 3|.

In Figs. 2 and 3, there is illustrated the preferred form of the device with the constituent elements thereof assembled in compact form. Referring to Fig. 2, the cabinet or housing 42 contains all of the elements of the system, as illustrated in Fig. 1, excepting the coil pairs I, 2 and H, l2. The casing is preferably provided with a sloping front panel 43, and thecathode raytube is supported within-the casing so that the flared end thereof and screen 3| lies substantially flush with panel '43 in a window opening 44 thereof. Thus, an operator may readily observe the image patterns formed on the screen. Opermounted on panel 43, as clearly illustratedf Switches l6 and 33 are mounted on panel 43 and controlled by operating knobs 41 and 48, respectively. A double push button switch is preferably used to combine switches 6 and 24, the op-' erating button of such switch being illustrated at 49. A-line switch 50 for controlling the supply of energy to lines 8 is mounted on the front vertical panel of'the cabinet and pilot light III is mounted behind lens 5|.

In order that the system may be controlled by the operator by means of a foot-operated switch (not shown) if desired, the jacks 5 and 23 above described are mounted together on the front vertical panel of the cabinet. By plugging suitable connecting conductors leading to a foot-operated switch into these jacks, the system may be controlled in this fashion. Two pairs of binding post terminals 52 and 53 are also provided on the front panel of the cabinet for connection to the pick-up coil assembly now to be described.

In cases'where the pieces to be tested and the standard piece take the form of small elements, such as bolts, screws and the like, I prefer to mount the inductively related coil pairs I, II and 2, l2 in a single casing 54, as illustrated clearly in Fig. 3. The coils (not visible) are mounted serted. Two sets of binding post terminals 51 and 58 are provided for connection to the main cabinet above described.

'I'heillustrations of Figs. 4 to 8 represent actual image patterns whichwere photographed from screen 3| during the testing of five pieces of steel. They reveal diflerences in the characteristics of the tested pieces from the standard piece which were not discernible under a microscope operated to cation. It will be noted that Figs. 4 and 5 are somewhat. similar, but nevertheless there is a distinct difference .between them. The piece whose test is represented by Fig. 4 diflered more widely from the standard piece than did give a thousand times'magniflthat represented by Fig. 5. This is evidenced by the greater lateral movement of the ray from a substantially straight line as shown by Fig. 4. Fig. 6 shows that the piece under test differed further in its characteristics from the standard piece and Figs. '7 and '8 show further differences in the characteristics of the pieces under test.

These illustrations show that pieces of similar or like physical and chemical characteristics will give substantially the same image pattern. Moreover, the exact characteristics, such as hardness, brittleness, etc., cause the images to take certain forms which may be readily recognized. Thus, an observer may determine at once the exact characteristics of any particular pieces which he wishes to test. The system is very useful in many instances as will be quite apparent. It is particularly useful in the testing of aeroplane and automobile parts where the highest degree of accuracy and precision is required. In many instances, pieces taken from the same lot vary widely in their characteristics. This is ofttimes true even though the entire lot has been subjected to the same treatment. By means of the present system, it is possible to quickly segregate the pieces comprising the lot according to their exact characteristics. It is also possible, of course, to pickseveral pieces at random from a lot and test them to see whether or not they as representatives of the lot have the desired characteristics. By virtue of its sensitivity and accuracy in giving a clear visual indication of the characteristics of a piece of metal, this system saves time, money and en ergy. In many instances, it has heretofore been necessary to scrap a lot of metal pieces even though some of them were satisfactory simply because it was impossible or impractical to separate the good from the bad pieces. The present system eliminates such wasteful practice by enabling the salvaging of the good pieces in a practical manner. The simplicity of operation of the .system is any important feature because it makes it possible for anyone to operate it.

In the preferred form of the invention, potentiometer 9 is given a value of 1000 ohms. The voltage of source l9 applied to the cathodes is 6 volts, while that of source I8 is 4.5 volts. The voltage of source 20 is 300 volts and a potential of 90 volts is applied to the plate of tube V. The

resistor included in the cathode-anode circuit of the cathode ray tube has a value of 2000 ohms, while the resistor in the circuit of cathode 21 has a value of 2.5 ohms. The capacity of condenser I is 2 microfarads. The purpose of this condenser is to enable a variation in the image pattern, when desired, by closing switch l6. Obviously by assigning a proper value to the condenser it may be made serve as a filter or by-pass element to eliminate harmonies or high frequencies or it may constitute with winding IS a resonant or tuned circuit. v The values above given may of course be varied without departing from the invention.

Although a single preferred embodiment of the invention has been described, it will be apparent that various modifications are possible and may be made without departing from the spirit and scopeof the invention.

I claim:

1. A portable device for determining the characteristics of a metal piece by comparison with a a metal piece of known characteristics, comprising a coil unit and a housing unit, said coil unit comprising a casing, a pair of serially connected coils within said casing, a pair of serially connected opposed coils within said casing and inductively associated respectively with said first coils, each pair of inductively associated coils being mounted in said casing so as to provide an air core or space into which ametal piece may be inserted, and terminals on said casing for connection to said coils, said housing unit comprising a cabinet or housing, a cathode ray tube with two sets of ray deflecting plates within said cabinet, 9. screen visibly mounted on said cabinet in the path of the cathode ray, circuits for connecting said opposed coils to one set of said ray deflecting plates. circuits for connecting the other coilsto a source of potential, circuits for connecting the other. set of ray deflecting plates to said source, and terminals on said cabinet for said circuits.

2. A portable device as set forth in claim; 1, said housing unit further comprising circuit control switches shunted by jacks mounted on said cabinet for optional use of toot-operated switches.

irownnn 'r. HALIDWELL. Jn. 

